HOLLYWOOD star Paul Giamatti is joining the cast of Downton Abbey for the Christmas edition of the period drama.

The Ides Of March, Cinderella Man and Sideways actor will portray Harold, the playboy brother of Cora Crawley (Elizabeth McGovern).

Giametti, 46, is the latest addition to the cast with Dame Kiri Te Kanawa, Tom Cullen, Julian Ovenden and Nigel Harman among the names who will be seen in the series later this year.

The feature-length Christmas edition is in addition to an eight-part series to be screened later this year which will see the return of old favourites Hugh Bonneville, Maggie Smith, Michelle Dockery and Jim Carter, as well as Shirley MacLaine.

Gareth Neame, the managing director of programme-maker Carnival Films, said: "We're excited that Paul Giamatti will be joining us on Downton to play Cora's brother Harold, the rather free-spirited uncle to Mary and Edith.

"We can't wait to see him work alongside Shirley Maclaine, who are both sure to upset the Granthams' apple cart in this year's Christmas Day episode."

In the seasonal edition of the show last year, viewers were shocked to be confronted by the death of popular character Matthew Crawley, played by Dan Stevens.